Erosion is a
comprehensive natural process of detachment and removal of loosened rock
materials and soils by exogenetic processes such as running water, ground water,
sea waves, wind, glacier etc. there are two types of erosion:

ØGeological erosion and

ØAccelerated erosion.

Erosion caused by
natural processes without being interfered by human activities is called
geological erosion. Accelerated erosion refers to the increased rate of erosion
cause by various land use changes effect by man.

Soil erosion is one
type of accelerated erosion, which is also called as Man-Included Erosion
because of greater impact of human activities than natural factors of soil
erosion. Soil erosion involves mainly two processes:

ØLoosening and detachment of
soil particles from the soil mass.

ØRemoval and transport of the
detached soil particles down slope, down stream or down wind.

.

Soil erosion is a
common characteristic of the fields of Assam. The highly productive and fertile
soils of Assam are now facing the serious problem of soil erosion like other
parts of the country. Riverbank erosion during high flood period in the valley
is a regular annual feature. The extent of loss to the bank erosion varies from
year to year depending on the severity of floods in the state. Thousands of
Mising tribe is under threat due to heavy soil erosion in Assam's Sumoi
Mari village. The Bramhaputra River floods the village situated in Majuli
quite often, causing immense erosion of fertile and cultivatable land. Over bank
flood due to breaches in the embankment, render the fertile cultivable land
unsuitable for crop production due to deposition of coarse sand on the surface
to a variable depth.

Various surveys
carried out by the Soil Conservation Department of Assam Government have
indicated towards the fact that Jhum cultivation is the major reason for
such widespread soil erosion in the state. As per Assam Government Revenue Dept.
records, an area of 6116 hectares of land was affected by soil erosion in Upper
Brahmaputra Valley and North Bank Plain zone during 1994.

In Assam the most
common type of soil erosion is loss of topsoil through surface run-off under
heavy precipitation and humid climate. Nearly 3.2 million hectares of land of
the plain districts of the state are vulnerable to topsoil erosion with varying
intensity.

Terrain deformation
through mass movement is another type of soil degradation, which is primarily
confined to the hill districts of Karbi Anglong and N.C. Hills covering an area
of about 1.53 million hectares. Another important type of soil erosion in the
state, which assumed serious proportion in the recent time, is the bank erosion
by the rivers.